plotly/dash v4.5.0rc0

Dash Version 4.5.0rc0

on GitHub

Added

• #3947 Make plotly-cloud a default install dependency of Dash instead of an optional extra, so the plotly CLI and Dash's cloud integration work out of the box. The dash[cloud] extra is kept for backward compatibility.
• #3930 Add shared storage: a backend-agnostic cross-process state manager (key/value with optional TTL, plus ordered replayable pub/sub) on every app via dash.ctx.shared_storage, started lazily and disabled with shared_storage=None. Ships LocalSharedStorage (default, in-memory with optional disk persistence), DiskcacheSharedStorage, and RedisSharedStorage for horizontally-scaled deployments; see .ai/ARCHITECTURE.md.
• #3931 Add streaming callbacks: an async def generator callback streams its yields to the browser as they are produced (dash.Patch yields apply incrementally). A browser's streams share one SharedWorker-hosted connection so they do not count against the per-host connection limit; closing a tab cancels its streams.
• #3977 Add partial WebSocket prop reads with get_prop(..., path=...). Closes #3975.
• #3765 Add opt-in partial pattern matching for callback Input, Output, and State via partial_pattern=True, so dictionary ID patterns can match component IDs with extra keys and combine with ALL/MATCH wildcards. Fixes #3764.
• #3646 Add experimental support for React 19 (default stays React 18.3.1); opt in with REACT_VERSION=19.2.4 or dash._dash_renderer._set_react_version("19.2.4"). Dash serves the umd-react package with a compatibility shim so component libraries built against React <=18 keep working; see .ai/ARCHITECTURE.md.
• #3925 Add optional callback request payload compression via compress_payload and compress_threshold callback parameters (default threshold 5,000 bytes), sending gzip payloads that Dash decompresses on Flask, FastAPI, and Quart. Fixes #3924.
• #3961 Added cursor position data (xPixel, yPixel) to dcc.Graph hoverData and clickData when hoveranywhere or clickanywhere is enabled in the figure.
• #3960 Rewrite dcc.Markdown and dcc.Link as Typescript components
• #3881 Added dash.remount, a wrapper for a callback-returned component that forces the renderer to remount it (resetting its internal state) instead of reconciling in place: the explicit way to reset a stateful component from a callback without changing its id.

Removed

• #3646 Remove React 16 support (16.14.0 is no longer an accepted value for REACT_VERSION / _set_react_version).

Changed

• #3986 Adjust _run_before_hooks in the fastapi backend to honor a response returned by a before_request function, matching the flask backend's behavior.

Fixed

• #3944 Fix dash.testing runner backend detection for wrapped FastAPI/Quart servers so threaded Flask-only options are not passed to ASGI runners.
• #3955 Unpin selenium in the testing requirements (was capped at <=4.2.0 from 2022) and require >=4.11.0, so it can drive current stable Chrome via Selenium Manager and stop the widespread CI flakiness.
• #3881 Speed up the renderer layout crawl (crawlLayout and its callers) by replacing curried-ramda path/pathOr lookups with direct property access on the hot path: ~16% faster Patch().append() into a large container, with no behavior change.
• #3881 Fix pattern-matching (MATCH/ALL/ALLSMALLER) callbacks getting quadratically slower as matching components grow; a new O(1) id->path index cuts an ALL update over 400 components from ~580ms to ~140ms (~4x), with no app changes.
• #3941 Fix the FastAPI and Quart backends opening a WebSocket connection on every page load even for apps with no WebSocket callbacks; the socket now opens only when actually needed. Fixes #3939.
• #3916 Fixed a regression where dragging multiple files into dcc.Upload would upload only the first file when multiple=True
• #3922 Fix dcc.Input(type="number") stepper behavior when only min is set.
• #3925 Use the proxied url as the Jupyter server url so DASH_PROXY is honored by the external url and inline iframe in notebooks.
• #3938 Fix dcc.Patch() re-running the initial callbacks of components already on the page (including every MATCH/ALL element) and wiping their user-edited persisted values. Fixes #3681 and #3937
• #3960 Fix dcc.Markdown not rendering <dccLink /> by using newer dependencies
• #3846 Fix callback-returned children being unmounted and remounted on every update instead of reconciled in place, which reset component state and slowed large subtrees 3-4x (regression introduced in 4.2.0 by #3570); use dash.remount to force a remount.
• #3881 Fix components rendered as props (eg. dcc.Dropdown option labels, dcc.Tab labels) crashing or failing to update when the host subtree was replaced by a callback; out-of-tree ExternalWrapper components now re-insert themselves and update in place.
• #3929 Fix components that set their own initial state on mount (eg. dash-bootstrap-components Tabs) not applying it on first render, because descendant layout hashes were reset on the first fresh render (regression introduced in 4.2.0 by #3570).
• #3948 Fix page getting progressively slower as callbacks append children